Heat exchanger with an expansion joint



April 19, 1960 H. D. HUGGINS HEAT EXCHANGER WITH AN EXPANSION JOINT Filed March 14, 1958 //v:/E/vT0A HOMBRE. I-IUBBINS ATTOFPAEJ/ Unitd States Patent HEAT EXCHAN GER WITH AN EXPANSION JOINT Homer D. Huggins, Racine, Wis., assignor to Modine Manufacturing Company, Racine, Wis., a corporation of Wisconsin Application March 14, 1958, Serial No. 721,382

2 Claims. (Cl. 257-154) This invention relates to heat exchangers withexpanrs'ion joints.

Ever since the conception of the light weight, high temperature heat exchanger, there has been a need for an expansion joint that is light weight, extremely compact, fluid tight, and capable of withstanding temperatures in the range of 500 F. to 1500 F. The exchanger is normally made of stainless steel or other high temperature metals where operating temperatures are of such a magnitude as to cause dimensional changes in the range of .0025 inch per foot to .15 inch per foot. The exchanger is usually designed to handle two fluids, air or gas, both of which flow through their respective passes without Lleakage between each other and to the outside. Where the exchanger employs a great plurality of tubes through which the hot fluid passes, and where the tubes are inounted and supported by a frame of mounting flanges .and side sheets which are exposed to the cold fluid, the tubes will normally tend to elongate under thermal expansion, and this action induces a stress in the exchanger unless an expansion joint is provided to allow for the thermal expansion. Various types of expansion joints have been employed in these heat exchangers, and they include a slip-type joint and an elementary bellows-type joint, but it is known that the slip-type joint is diflicult to make and keep fluid-tight, and the known bellowstype joint is utilized where ample radii can be provided at the corners of the joint in plan view. This means that the conventional bellows joint can be used where space is of no consideration since the joint requires maxi mum space. In certain applications and particularly in aircraft, space and weight are of the utmost importance, and performance requirements dictate the need to utilize even the corner areas of the exchanger for heat transfer surface.

Accordingly, it is a general object of this invention to provide a heat exchanger with an expansion joint which is light weight, fluid tight, can withstand the high temperatures in the range referred to above, and which utilizes the maximum space available in the exchanger to provide maximum exchanger efliciency. In considering this object, it should be understood that the reference to making the expansion joint fluid tight means the hot fluid and the cold fluid are both in fluid tight passes, and neither fluid is permitted to escape beyond the circuits of the heat exchanger system including the headers and inlet and outlet conduits of the heat exchanger. Also, in accomplishing this object, the expansion joint is made of light gage metal of the same or similar composition as the exchanger core and casing, and the metal has the characteristics of withstanding maximum deflection without assuming a permanent set.

Other objects and advantages will become apparent upon reading the following description in conjunction with the accompanying drawings, wherein:

Fig. 1 is a top plan view of an exchanger incorporating a preferred embodiment of this invention and show- 2 ing a fragment of the base to which the exchanger is bolted.

Fig. 2 is a front elevational view of the exchanger shown in Fig. l but with the base removed.

Fig. 3 is a right side elevational view of the exchanger shown in Fig. 2.

Fig. 4 is an enlarged sectional view of a. fragment of the exchanger as seen along the line 4-4 of Fig. 1.

Fig. 5 is a sectional view similar to that of Fig. 4 but showing an alternative arrangement of some parts.

Fig. 6 is an enlarged sectional view of a fragment of the exchanger as seen along the line 66 of Fig. 1.

The same reference numerals refer to the same parts throughout the several views.

The drawings show the exchanger 10 having a front frame piece 11 and a rear frame piece 12 with these frame pieces having the openings 13, as: shown in Fig. 2, for attaching the exchanger to the base members 14 and 16, as indicated in Fig. 1. It should. thus be understood that the exchanger 10 includes a rigid and inflexible frame including the parts 11 and 12 and two side or end pieces, such as the right end piece 17 shown in Fig. 3. Thus, the left and right ends of the exchanger are enclosed by the end pieces 17 while the front and rear faces of the exchanger are open so that one fluid can flow through the exchanger frame from the front to the rear of the exchanger which would, of course, be transverse to the plane of the paper, as viewed in Fig. 2. The frame thus defines what can be termed a first fluid pass with the frame being fluid tightly attached or attachable to the base or mounting pieces 14 and 16 so that the first fluid pass is separate and fluid tight.

The lower end of the exchanger has a fluid header 18 fluid tightly secured thereto, and gusset plates 19 provide support and attaching means for the header 18. A second and narrower header 21 is also fluid tightly attached to the bottom of the exchanger and extends the length of the header 18 and has a fluid inlet connection 22 in communication with the header 21 so that fluid can enter the header 21 through the connection 22. Thus, it can be said that the exchanger takes the form of a U shape with the right and left hand sides, such as the sides 17, and the bottom, consisting of the headers described, forming the U with the central and upper ends of the exchanger frame being open except for the cross pieces of the frame 11 shown in Fig. 2.

It will, of course, be seen that a plurality of tubes 23 are disposed in the exchanger frame, and the tubes are actually arranged in three sets or banks, as shown in Fig. l, with, of course, each set extending across the entire width of the exchanger so that the full interior of the exchanger is occupied by the tubes which are closely spaced apart, as shown in Fig. 2 also. The application of this exchanger is such that the tube spacing within each bank is shown to be less than the diameter of the tubes. Fluid entering the inlet 22 and the header 21 will flow through the first bank of tubes which are in the uppermost position in Fig. l, and the upper ends of the tubes open into a wide header 24, which is incorporated and attached in the exchanger as explained hereinafter. The header 24 permits the fluid to pass through the middle bank of tubes and downwardly into the lower and wide header 18 from where the fluid will flow upwardly in the third bank of tubes so that the fluid will enter a narrow header 26, and it can then flow to the outlet 27. In this arrangement, the tubes are fluid tight to the exchanger and form a second fluid pass. Also, in the heat exchanger shown, it should be understood that the headers 24 and 26 are welded together along their contiguous edges and they are relatively heavy and have parts, such as a fuel tank port 28, sub-systems port 29, and a bracket 31 all mounted on the header. This condition means that Patented Apr. 19, 196(1 the headers must be sturdy and must be well supported and, of course, these factors are considered in this invention.

.-Fi gS. 4- and ,5- show that a plate 32, is physically and:

. 4 While two embodiments of this invention have been shown and described, it should be obvious that certain changes could be made in these embodiments, and the scope of the invention should, therefore, be limited only by the appended claims.

What is claimed is:

1. A heat exchanger comprising an uprightly disposed rectangular frame with open opposite faces defining a first fluid pass for the flow of fluid therethrough, a secvides support between the plate 32 and the upper ends of i the tubes 23 with respect to the headers24 and 26 so that the weight of the headers and their attending parts is on the tubes 23.

Theirnportant feature of theinvention is the provision of the'expansion bellows-type joint 34 which is rectangulat-in plan area, as viewed in Fig. 1, and, therefore, the joint extends'around the perimeter of the headers 24 and 26. It will be seen that the joint is comprised of a plue rality ofrectangularly shaped but open center sheets which are welded together at alternate layers on the inside and outside of the sheets to present the two weld lines,36 and 37-, as shown in Fig. 4. Also, the upper edge of the bellows 34. is welded at 38 to be fluid tight with theheaders 24 and 26, and the lower edge of the bellows is-welded at 39 to be fluid tight with the sidcs 17 and the frame 11. With this overall arrangement and assuming, for instance, that hot fluid is passing through the second fluid pass, defined by the tubes 23, and cold fluid is passing through the first fluid pass, the tubes 23 will elongate under thermal expansion, and this will cause theheaders 24 and 726 to rise as the bellows type joint 34 is expanded to allow for and accommodate the expansion in the tubes 23. Of course, at all times the tube passes are retained absolutely fluid tight with respect to the first fluid pass.

Fig. 5 shows a variation of the bellows and the exchanger side, and in this instance, the side 17 is replaced by a side 41, and the bellows 42 is again of the rectangula r shape in plan view of Fig. 1, butwith the arrangernent of the bellows as shown in Fig. 5, upon thermal elongationof the tubes 23, the 'bellows 42 will contract or be compressed as the side 41 remains in position, and the headers 24 and 26, along with the plate 32, move upwardly to contract the bellows 42.

'Referring again to Fig. 1, it is important to understand that the bellows is of a rectangular shape so that the second fluid pass, which is comprised of the tubes 23, can occupy the entire plan area of the exchanger as the tubes 23 are disposed in the four corners of the rectangularly shaped bellows 34. This, of course, provides maximum efficiency in the exchanger since the four corners are fully utilized as no radius is required in the formation of the bellows, as it encompasses the upper headers of the exchanger. It should also be noted that no particular stress, due to the weight of parts of the exchanger, is placed upon the expansion joint since the plate 32 is welded to the headers 24 and 26 and, in addition, the supportwmembers or columns 33 are attached between the plate. 32 and the header 24 Thus, weight of the header 24 and the header 26 is directly on the plate 32 whilethe expansion joint 34 need only retain fluid-tight relation between the parts to which it is attached.

0nd fluid pass consisting of a plurality of spaced apart;

tubes uprightly disposed. in said first fluid pass, said passes being fluid tight with respect to each other for conductance of respective fluids through said passes at diiferent temperatures, a header in fluid flow communication with said tubes, a rectangular tube bundle plate rigidly and fluid tightly attached to both one common end of said tubes and to said header and with said tubes occupying the full area of said plate including the four corners thereof, and a bellows type of expansion joint interposed between and fluid tightly attached at one end to said header and at the other end to said frame of said exchanger and disposed behind said frame between the latter and said header and in said first fluid pass for rendering the latter fluid tight, said joint being formed of layers of r eetangularlyshaped plates having four right angled corners and being fluid tightly connected together at alternate edges of said layers.

2. A heat exchanger comprising an upright and box like frame including both a front and a'rear rectangular piece and two enclosed sides and an enclosed bottom for defining a portion of a first fluid pass with an open front and rear for the flow of fluid through said frame, a plurality of tubes uprightly disposed in said frame between the top and bottom thereof for defining a second fluid pass, a rectangular plate rigidly and fluid tightly attached to the topcnds of the outer circumferences of said tubes for fluid tightly separating said fluid passes and being disposed below the plane between the upper edges of said rectangular pieces, a header disposed over and fluid tightly attached to saidplate and being in fluid flow communication with said top ends of said tubes, support members connected between said plate and said header forfurther securing the latter two together in a unit relationship so that said uprightly disposed tubes provide structural support forsaidheader, and a rectangular shaped bellows type of expansion joint disposed below said upper edges of said rectangular pieces and behind the projected area thereof and being attached directly at one end to said frame and being fluid tightly sealed therewith and attached directly at the other end to said header outside of said second fluid pass and being fluid tightly sealed with said header and disposed to define the remainder portion of said first fluid pass for movement of said unit independent of and with respect to said frame in response to thermal conditions of said exchanger.

References Cited in the file of this patent UNITED STATES PATENTS 1,604,197

Rushmore Oct; 26,1926

2,232,936 Bimpson ..7 Feb. 25,- 1941 2,505,790 Panthofer May 2, 1950 2,653,799 "Stahn et al. Sept. 29 1953 2,752,172 Ziebold June 26, 1 956 FOREIGN PATENTS 1,11 1,990 France Mar. 7, 1956 

